Spring grinder



Oct. 16, 1956 H. c, c so 2,766,561

SPRING GRINDER Filed Dec. 10, 1954 i 4 Sheets-Sheet l o o o w w IN VEN TOR. Q Q Q 194 20.49 '5: z az z m ZZZ 7T Oct. 16, 1956 H R, c so 2,766,561

SPRING GRINDER Filed Dec. 10, 1954 4 Sheets-Sheet 2 v f! p s I INVENTOR. [rig W40 c. 5 ('iJjW/V Oct. 16, 1956 H, c. R. CARLSON 2,766,551

SPRING GRINDER Filed Dec. 10, 195 .4 Sheets-Sheet 3 INVENTOR. B15065 61/23 CZZ QJJ'Q V Oct. 16, 1956 H. C. R. CARLSON SPRING GRINDER 4 Sheets-Sheet 4 Filed Dec. 10. 1954 INVENTOR.

SPRING GRINDER Harold C. R. Carlson, Brooklyn, N. Y.

Application December 10, 1954, Serial No. 474,333

16 Claims. (Cl. 51114) This invention falls within the field of grinding equipment and is most pertinent to abrasive disc grinders used for grinding two parallel surfaces simultaneously.

Although the present invention is applicable to the grinding of a wide variety of machine elements such as washers, piston rings, ball bearings, shafts and ceramic products, it is primarily intended for effecting a parallel grinding of the ends of coiled compression springs.

This process is customarily accomplished by a number of different types of spring grinding machines, commonly employing two oppositely aligned, motor driven grinding discs, which are rotatable in the same direction. With this arrangement, the required parallel grinding may be performed by inserting the springs between the grinding surfaces and laterally moving one or both grinding discs so as to produce a concurrent contact between these surfaces and the ends of the springs.

However, while this operation has been applied to the large scale production of coiled compression springs, the machines which currently make use of it suffer from various diificulties. Foremost among these is the fact that it is common practice to located the holder for the springs to be ground and/ or its supporting member between the grinding discs so that either member or both cannot be removed without disassembly and consequent shutdown of the machine; and in the absence of such disassembly, such a manner of location prevents the grinding wheels from being brought together for dressing purposes, and has given rise to the incorporation within some of theconventional machines of specially designed wheel dressing equipment. Furthermore, when the work supporting equipment is located between the grinding discs, full utilization of the available grinding surfaces is denied since a portion thereof is necessarily occupied at all times by at least some part of the work holder and/ or its supporting member.

Another disadvantage in the conventional grinding machines arises from the fact that when the coil springs are composed of certain metals, the rotation of the grinding discs in the same direction frequently produces an undesirable splitting or tearing of the end surfaces of the springs and necessitates the grinding of only one of such end surfaces at a time.

Moreover, specially designed supporting features must be provided in a number of the currently used machines if it is desired to prevent excessive overhang of the spindles upon which the grinding discs are mounted. Here also, it is a common practice to provide hydraulic or electrical power for effecting the required lateral movement of both grinding surfaces, independently of the motor which drives them, or, in the alternative on the part of only one grinding disc and motor unit. The former disposition may require specialized coupling equipment between the motor and grinding discs; and the latter arrangement may result in greater wear upon the movable disc and motor units as contrasted to the wear incurred by the stationary unit.

A further difficulty with the currently available grind- 2,766,561 Patented Oct. 16, 1956 Ice ing machinery is the fact that this equipment usually occupies considerable space and is frequently floor mounted because of its weight.

The present invention solves these problems by using a compact, horizontal, hand-operated double disc type bench grinder, which employs a set of grinding discs rotatable in opposite directions and makes available for grinding purposes the entire surfaces of these discs since no part of the work holder or its support is permanently disposed between the grinding surfaces. On the contrary, the work support is ingeniously positioned at a position equidistant from and below the grinding discs, and the work holder is manually removable in the ordinary course of grinding operations. This location thereby permits both grinding surfaces to be moved laterally into contact with each other for wheel dressing purposes, thus eliminating the need for auxiliary dressing equipment or disassembly of the grinder for such purposes. However, where desired, a wheel dressing device may be held by the work holder and manually inserted between the grinding discs, without causing shutdown of the machine.

The present invention also uses direct driven grinding disc and motor units which are both laterally movable into contact with the work by means of a simple hand feed mechanism, thereby avoiding the possibility of uneven wear upon one of the grinding units as compared with the other and the need for elaborate electric or hydraulic power equipment with its accompanying bulk and expense.

The drawings illustrate some embodiments of this invention.

Figure 1 shows a perspective view of one arrangement of the invention.

Figure 2 is a centrally located, transverse cross-section thereof showing the spring holder in a position outside the space between the grinding discs.

Figures 3 and 4 illustrate two dilferentt types of spring holders which may be used with the grinding unit.

Fig. 5 is a perspective view of the baseplate used in the said arrangement of the invention, the internal mechanism of the baseplate also being shown in this view.

Figure 6 is an enlarged fragmentary view showing the vertical shaft-supporting member which is incorporated within the said baseplate.

Figure 7 is an enlarged perspective view of the gear mechanism illustrated in Figure 5.

Figure 8 illustrates a perspective view of another arrangement of the gear mechanism which may be used in a modified form of the invention.

As shown in the drawings, the embodiment of the invention illustrated in Figure 1 to 7 comprises as its main operative elements a pair of oppositely aligned, directly driven, horizontal grinding heads 10, 11 having a common longitudinal axis. Each of these grinding heads 10, 11 incorporates a grinding disc 12, 13, having a smooth grinding surface 12a, 13a without any center hole or other perforation, although perforations may be used if desired, a motor 14, 15 and means for supporting such disc 12, 13 and affixing it to the motor shaft 16, 17. Thus, the discs 12, 13 are supported by circular plates 18, 19 which in turn are secured to hubs 20, 21 mounted upon the motor shafts 16, 17 in a position close to the motors 14, 15 so that the overhang of the shafts 16, 17 is kept to a minimum. The motors 14, 15 are equipped with special thrust bearings suitable for withstandingthe end thrust that commonly occurs during grinding. Cooling fans 14a, 15a may also be mounted upon the motor shafts 16, 17 so as to circulate a quantity of cool air over the motors 14, 15 during their operation and blow the grinding dust into the work space area where it may be collected and removed.

These motors 14, 15 are secured upon rectangular plates 22, 23 maintained in two pairs of ways 24, 25 so that the surfaces 120, 13a of both grinding discs 12, L: are aligned parallel to each other and the grinding heads 15 11 may be slidably separated or brought together. Each pair of ways 24, is separately adjustable and may be rigidly fastened to a baseplate 26 by a suitable number of screws 27.

As illustrated in Figure 5, on the rear side 26g of the baseplate 26, which is normally furthest from the operator of this form of the invention, to avoid accidental operation of the machine, there are conveniently located separate starters 28, 29 for each of the motors 14, 15 so that the grinding discs 12, 13 driven thereby can be rotated independently or concurrently in the same or opposing directions, as indicated by the arrows in Figure l. A forward button 28a, 29a, a reverse button 28b, 29b and a stop button 280, 290 for producing a forward or reverse rotation of the grinding discs 12, 13 or for stopping the rotation of the grinding discs 12, 13, as desired, are located on each of the said starters 28, 29. Thus, while the grinding discs 12, 13 customarily contact the work to be ground while they are rotating in the same direction, where the work material will receive a superior grinding finish by opposite rotation of the grinding discs 12, 13 or where only one side of the work is to be ground, these operations may be accomplished with equal facility by appropriate adjustment of the starter buttons 28a, 28b, 28c, 29a, 29b, 230. Moreover, when the grinding discs 12, 13 are rotated in opposite directions they may be brought into contact so as to dress or grind each other smoothly and true.

A hand lever 30 is also clamped in a normally horizontal position upon a gear driver shaft 31 projecting from within the baseplate 26 through its front side 26a. Since this shaft 31 is connected to both grinding heads 10, 11 by a train of gears having a high mechanical advantage, a relatively slight pressure in a downward direction upon the hand lever 30 is sufficient to bring both grinding heads 10, 11 into concurrent contact with the work and maintain that position for as long as is required. Since this approximately horizontal position of the hand lever 30 corresponds with an open position of the grinding heads 10, 11 an upward movement of the lever 30 effects a disengagement of the grinding discs 12, 13 from the work.

As shown in Figures 5 and 7, the gear train actuated by the hand lever 30 includes a driving pinion 32 mounted upon a portion of the driver shaft 31 located within the baseplate, 26v and, in mesh with, a first intermediate spur gear 33. afiixed upon a parallel intermediate shaft 34. At one end of this intermediate shaft 34 there is also mounted an intermediate pinion 35 in mesh with a second intermediate spur gear 36 secured upon a parallel driven shaft 37. The driven shaft 37 also carries a driven pinion 38 which meshes concurrently with upper and lower horizontal racks 39, 40 so that for any given rotation of the driven pinion 38 opposite linear movements of the racks 39, 40 will be produced.

All of the shafts 31, 34, 37 are rotatably supported in suitable bushings 41, 42, 43 contained in the front side 26a of the baseplate 26 and in a central vertical member 26b, shown in Figures 5 and 6, having two split portions 26c, 26d located within the interior of the baseplate 26 and integral therewith. The pinions 32, 35, 38 and spur gears 33, 36 are mounted upon their respective shafts 31, 34, 37 by suitable keys, and, with the exception of the driven pinion 3.8 which is maintained laterally by the split portions 26c, 26d of the vertical member 26b, are prevented from undergoing any undesirable lateral displacement by a number of collars 44 suitably fastened to the shafts 31, 34, 37-.

The upper rack 39 carries a block 45 which is slidable within a first longitudinal slot 47, located near one end of the upper surface 262 of the basepl'ate 26, and removably secured to the lower surface of one of the rectangular plates 22 in the vicinity of the slot 47.

The lower rack 49 is supported by a roller 48 mounted on the said intermediate shaft 34 and retained between said vertical sections 26c, 26d as are both of the racks 39 and 40. The said lower rack 40 is also connected by bolts 40:: to a horizontal angle member 49 which is in turn connected to another block 50, this block being slidable within a second longitudinal slot 51 located near the other end of the upper surface 26@ of the balseplate 26 and removably secured to the lower surface of the remaining plate 23 in dhe vicinity of this second slot 51.

With this arrangement, the grinding heads 19, 11 may simultaneously be moved together or apart, as desired, by simply depressing or raising the hand lever 30 so as to actuate the gear train.

It is noteworthy that a small compression spring 52 is coiled around a portion of the driver shaft 31 and is supported upon the inner surface of the front side 26a of the baseplate 26 and upon the side of the collar 44 adjacent to the driving pinion 32. This arrangement permits the normal position of the hand lever 30 to be adjusted to any convenient angular location by simply pulling outwards upon the said hand lever 30 so as to disengage the driving pinion 32 from the first intermediate spur gear 33, turning .the hand lever 30 to the desired angular location and then allowing the compression spring 52 to expand and thereby force the said pinion 32 to re engage the said intermediate spur gear 33. The frictional resistance to mot-ion of the gear train and its connected parts will then maintain the lever 30 in position.

The overall distance that each grinding head 10, 11 is permitted to move and hence the depth to which it will grind the work, is limited by an adjustable stop rod 53 threadedly mounted within one end 26f of the baseplate 26. This rod 53 may be screwed into contact with the lower rack 40 so as to limit its horizontal movement and thereby restrict the movement of the gear train and grinding heads 10, 11 attached thereto. A suitable handle 54 is used for turning the stop rod 53 and an internally threaded locking member 55 is rotatably mounted thereon and contactable with the exterior surface of the end 26 of the baseplate 26 so as to exert a strong pressure upon this surface and thereby lock the position of the rod 53.

The grinding discs 12, 13 and portions of their supporting means, as well as the space between these discs 12, 13, are enclosed within a dust guard 56 which is suitably supported upon the baseplate- 26, This dust guard 56 incorporates appropriate stiffening braces 57 and a hinge 58 attached to a pair of laterally adjustable front guards 59 having a suitable lifting knob 60 which allows access to the grinding area when desired. Thus the front guards 59 can be adjusted so as to cover almost the entire grinding space in front of the operator, with the exception of the area required for insertion of the work between the grinding discs 12, 13, thereby preventing the escape of dust and debris from the grinding area to the vicinity of the user of this form of the invention and protecting him from accidental touching of the grinding discs 12, 13 during their operation and breakage thereof resulting in flying particles of the said discs 12, 33. However, the sides of the dust guard 56 are left open so that the cooling fans 14b, 15b will blow the grinding dust into the work area where it will settle to the surface of the baseplate 26 below and may be disposed of as hereinafter described.

The dust guard 56 also covers a substantial portion of a horizontal frame support 61 which is disposed in a position transverse to the longitudinal axis of the baseplate 26 and projects outside the dust guard 56 from within the grinding space; The projecting portion of this support 61 is affixed to a bracket 62 mounted upon the front side 26a of the baseplate 26' and its remaining portion is directly attached to the baseplate 26-. A horiz'ontal guide bar 63 is also mounted upon the frame support 61 and both guide bar 63 and support 61 are located at an elevation below the lower surfaces 12b, 13b of the grinding discs 12, 13 so as to be clear of them when they are brought together for dressing purposes or for grinding the work material.

When the grinding heads 10, 11 are in operation, a manually slidable frame 64 is used to retain a quantity of springs 65, or other work to be ground, and is inserted between the grinding discs 12, 13 where it is maintained by the operator and held by the support 61. The discs 12, 13 may then be brought into contact with the ends of the springs 65 by depressing the hand lever 30, and thereby accomplishing the desired grinding. The frame 64 may be moved back and forth between the grinding discs 12, 13 to produce a faster and more even grinding, and may be removed from the work area upon completion of the grinding process by simply releasing the hand lever 30 and withdrawing the frame 64. It is to be noted that since the grinding surfaces 12a, 13a contain no holes of any kind these surfaces 12a, 13a are fully available for grinding, especially in view of the fact that the frame support 61 does not interfere with or cover any portion of the said surfaces 12a, 13a.

The lower portion 66 of the frame 64 contains a groove 67 loosely engageable with the aforesaid guide bar 63 so that when the frame 64 is located between the grinding discs 12, 13 it will be turned parallel to their surfaces 12a, 13a without encountering any resistance from the guide bar 63. This lower portion 66 is fastened to an upper portion 68 having a suitable handle 69 and a number of holes 70 tapped to accommodate a quantity of screw-ball clamps 71. These clamps 71 are atiixed to two straps 72, 73 which may be adjusted to receive and securely retain the work to be ground. In the case of coil springs 65, they may be inserted in a rectangular wooden block 74 so as to project from a number of holes 75 drilled therein, and the entire block 74 may be clamped within the slidable frame 64 so as to be available for re ception within the work area between the grinding discs 12, 13. (As an alternative to this wooden block 74, a quantity of metal tubes 74a may be clamped within the frame 64, or the frame 64 itself may be replaced by a wood or metal paddle 64a having on one portion a number of holes adapted to hold the springs 65 and at the other portion a manually engageable handle. Such a paddle 64a is especially useful for the reception of shorter springs than can be used in the frame 64.)

There is also located in the upper portion 68 of the frame 64 a number of threaded holes 76 adapted to receive an appropriate wheel dresser 77. While such a dresser 77 need not ordinarily be used since the grinding discs 12, 13 may be operated to dress each other, as described above, this provision for such a dresser 77 is made since it may occasionally be desired for purposes such as the dressing of only one grinding disc. In the latter instance, the frame 64 may be placed upon the support 61 in a position beside the horizontal guide bar 63 so that the said frame 64 and the wheel dresser 77 which may be carried therein will be closer to one of the said grinding discs. In this position, the wheel dresser 77 will thus be contactable with only that grinding discs which it is desired to dress, contact therewith being maintainable by manual pressure for as long as is desired. The frame 64 carrying the said dresser 77 may also be placed upon the guide bar 63 for dressing purposes if this is deemed convenient.

Below the work area between the grinding discs 12, 13 there is located an inclined well 78 which is integral with the baseplate 26 and which serves to receive grinding dust and debris from the grinding and dressing operations which is retained within the work area by the cur rents of air from the cooling fans 14a, 15a. This well 78 slopes to the rear side 26g of the baseplate 26 and terminates in a circular aperture 79 which is adapted for communication with a suction hose 80 so that the dust and debris may be removed as desired.

It is to be noted that if it is desired to move or use only one grinding head, 10 or 11, either of the blocks 45 or 50, may be disconnected from the rectangular plates 22, 23 supporting the motors, 14, 15, as is convenient, thereby reducing the pressure required to depress the hand lever 30, the disconnected grinding head being affixable in a position in or out of contact with the work by suitable locking means (not shown).

It is also noteworthy that the baseplate 26 is cemented to a soft rubber cushioning strip 81 suitable for reducing noise and absorbing any vibrations accompanying the use of the invention.

Another form of the inventiton, as shown in Figure 8, eliminates the necessity for the vertical shaft-supporting member 26b, and instead provides for supporting the gear mechanism set forth hereinabove in the front and rear sides, 26a and 26g, of the baseplate 26.

The forms of the invention hereinabove described are suitable for very economical grinding of compression springs having wire diameters ranging from .010 inch to .0625 inch and outside diameters ranging from A; inch to 1 inch. Compression springs of larger wire diameters or greater outside diameters can also be ground in these machines but at a lower rate of production. It is also to be noted that compression springs having quite great lengths can be ground in these units.

However, while the embodiments of the present invention described above are primarily intended as adjuncts to the larger mass production spring grinders usually adapted to handling great quantities of springs at a time, and are especially suited for handling lesser quantities of springs where a large amount of power is not required for grinding purposes, their novel features may be used to advantage in other forms of the present invention which have greater capacities and are adapted to mass production use.

The invention can be used for dry grinding but suitable liquids for wet grinding may be availed of if desired.

The embodiments of the invention illustrated and described hereinabove have been selected for the purpose of clearly setting forth the principles involved. It will be apparent, however, that the present invention is susceptible of being modified in respect to details of con-. struction, combination and arrangement of parts which may be resorted to without departure from the spirit and scope of the invention as claimed. I

Having thus described my invention, I claim as new and desire to secure by Letters Patent of the United States:

1. An improved spring grinder comprising in combination a pair of horizontally aligned, direct driven, rotatable grinding heads slidably mounted upon a baseplate, manually operable means for moving. the said grinding heads towards and away from each other, said means being located within the said baseplate and connected to the said grinding heads, means for supporting between the said grinding heads a removable frame containing a quantity of coil springs, said supporting means being located upon the said baseplate at a significant distance below the said grinding heads, and a shield located over the area between the said grinding heads and supported upon the baseplate above a debris disposal means incorporated in the said baseplate, and blower means adapted to enclose and restrict the grinding debris to the area under said shield.

2. A device as set forth in claim 1, said manually operable means comprising a hand lever aflixed upon a portion of a gear driver shaft projecting from within the said baseplate, the said shaft also extending within the interior of the baseplate and having a driving pinion aflixed thereon and engaged with a first intermediate spur gear affixed upon a parallel intermediate shaft, said intermediate shaft also having an intermediate pinion aflixed thereon and engaged with a second intermediate spur gear atfixed upon a parallel driven shaft, the said driven shaft also having a driven pinion affixed thereon and concurrently engaged with upper and lower horizontal racks, the said upper rack being mounted upon a block slidably located within a first longitudinal slot in the upper surface of the said basepiate and removably secured to the lower surface of one of the said grinding heads, the said lower rack being supported by a re ler suitably mounted upon the said first intermediate shaft, the said lower rack also being secured to a horizontal angle member which is in turn mounted upon a second block slidably located within a second slot in the upper surface of the said baseplate and removably secured to the lower surface of the other of the said inding heads, all of the said shafts being rotatably mounted within the front and rear sides of the said baseplatc.

3. A device as set forth in claim 1, said manually operable means comprising a hand lever afiixed upon a portion of a gear driver shaft projecting from within the said baseplate, the said shaft also extending within the interior of the baseplate and having a driving pinion affixed thereon and engaged with a first intermediate spur gear aflixed upon a parallel intermediate shaft, said intermediate shaft also having an intermediate pinion affixed thereon and engaged with a second intermediate spur gear affixed upon a parallel driven shaft, the said driven shaft also having a driven pinion aifixed thereon and concurrently engaged with upper and lower horizontal racks, the said upper rack being mounted upon a block slidably located within a first longitudinal slot in the upper surface of the said baseplate and removably secured to the lower surface of one of the said grinding heads, the said lower rack being supported by a roller suitably mounted upon the said first intermediate shaft, the said lower rack also being secured to a horizontal angle member which is in turn mounted upon a second block slidably located within a second slot in the upper surface of the said baseplate and removably secured to the lower surface of the other of the said grinding heads, all of the said shafts being rotatably mounted in the front side of the said basepl'ate and with-in the split portions of a vertical member which is integral with the said baseplate and centered upon the longitudinal axis thereof, the said split portions retaining the said roller, the said driven pinion and the said upper and lower racks against lateral displacement.

4. A device as set forth in claim 2, the said driving pinion being biased against disengagement from the said first intermediate spur gear by a compression spring mounted upon the said gear driver shaft between the said pinion and the front wall of the said baseplate, the said gear driver shaft being slidable by manual pressure along its longitudinal axis to a position wherein the said driving pinion is disengaged from the said first intermediate spur gear, the said hand lever being turnable in this disengaged position to any desired angular location, the said compression spring cooperating to re-engage the said driving pinion with the said first intermediate spur gear when the desired angular location has been reached and the said manual pressure has been released.

5. A device as set forth in claim 3, the said driving pinion being biased against disengagement from the said first intermediate spur gear by a compression spring mounted upon the said gear driver shaft between the said pinion and the front wall of the said basepla-te, the said gear driver shaft being slidable by manual pressure along its longitudinal axis to a position wherein the said driving pinion is disengaged from the said first intermediate spur gear, the said hand lever being turnable in this disengaged position to any desired angular location, the said compression spring cooperating to re-engage the said driving pinion with the said first intermediate spur gear when the desired angular location has been reached and the said manual pressure has been released.

6. A device as set forth in claim 1, said removable frame comprising a grooved lower portion affixed to an inverted Uashaped upper portion having a suitable handle and threadedly mounting 'a plurality of adjustable clamps attached to at least one movable strap, the said strap being contactabl with a suitable work holder adapted to projectably receive within a number of holes therein a plurality of coiled compression springs, the said upper portion also having a plurality of threaded holes adapted to receive and removably retain a wheel dresser.

7. A device as set forth in claim 1, said removable frame comprising a thin rectangular paddle having a suitable handle and a number of holes adapted to projectably receive a plurality of coiled compression springs.

8. A device as set forth in claim 1, said shield comprising a thin sheet-like guard suitably stifiened and having a cross-sectional conformation of an inverted U, the said guard having open sides and a pair of laterally ad justable, hinged front members which incorporate at least one lifting knob.

9. A device as set forth in claim 1, each of the said grinding heads comprising a grinding disc having an unperforated grinding surface, a circular plate afiixed to the said disc and attached to a suitable hub mounted upon the shaft of a motor having a suitable thrust bearing, the said shaft also mounting a partially enclosed cooling fan which cooperates with the said motor to circulate a cooling flow of air thereabout and also blows dust and debris escaping from the area between the grinding heads back into the said area, the said motor being suitably mounted upon a rectangular plate.

10. A device as set forth in claim 1, each of the said grinding heads being independently rotatable in a forward as well as a reverse-direction, the said grinding heads being operable by a pair of electrical control switches mounted upon the rear side of the baseplate.

11. A device as set forth in claim 1, said supporting means comprising a horizontal frame disposed transversely to the longitudinal axis of the baseplate and supported upon the said baseplate and upon a bracket mounted upon the front side of the said baseplate, the said horizontal frame also incorporating upon its upper surface a horizontal guide bar engageable with the said removable frame.

12. A device as set forth in claim 1, said baseplate comprising a hollow base having two pairs of parallel ways mounted upon its upper surface, the said upper surface being longitudinally slotted in two places and sloping transversely in its central portion, the said transverse slope terminating at the base of a circular aperture 10- eated in the rear wall of the said baseplate, the said baseplate having front and rear walls rotatbly supporting the sid manually operable means, the said baseplate also being mounted upon a vibration absorbent cushion.

13. A device as set forth in claim 1, said baseplate comprising a hollow base having two pairs of parallel ways mounted upon its upper surface, the said upper surface being longitudinally slotted in two places and sloping transversely in its central portion, the said transverse slope terminating at the base of a circular aperture located in the rear wall of the said baseplate, the said baseplate having a split vertical member straddling each of the said longitudinal slots and integral with the said upper surface, the said split member being contained within the said baseplate, the front wall of the said baseplate and the said split member rotatably supporting the said manually operable means, the said baseplate being mounted upon a vibration absorbent cushion.

14. An improved spring grinder comprising in combination a pair of horizontally aligned, direct driven grind ing heads each of which has a grinding disc with an unperforated grinding surface, a circular plate affixed to the said disc and attached to a suitable hub mounted upon the shaft of a motor having a suitable thrust bearing and a partially enclosed cooling fan which cooperates with the said motor to circulate a cooling flow of air thereabout, the said grinding heads each being independently rotatable in a forward as well as a reverse direction and operable by an electrical control switch, the said motor being suitably mounted upon a rectangular plate slidably retained Within a pair of parallel ways mounted upon the upper surface of a hollow baseplate supported upon a vibration absorbent cushion and having front and rear walls rotatably retaining a gear driver shaft turnable by a suitable hand lever atfixed upon the front end thereof, the said shaft also extending within the interior of the baseplate and having a driving pinion afiixed thereon and engaged within a first intermediate spur gear affixed upon a parallel intermediate shaft, said intermediate shaft also having an intermediate pinion afiixed thereon and engaged with a second intermediate spur gear affixed upon a parallel driven shaft, the said driven shaft also having a driven pinion affixed thereon and concurrently engaged with upper and lower horizontal racks, the said upper rack being mounted upon a block slidably located within a first longitudinal slot in the upper surface of the said baseplate and disconnectably bolted to the lower surface of one of the said rectangular plates, the said lower rack being supported by a roller suitably mounted upon the said first intermediate shaft, the said lower rack also being secured to a horizontal angle member which is in turn mounted upon a second block slidably located within a second slot in the upper surface of the said baseplate and disconnectably bolted to the lower surface of the other of the said rectangular plates, the said lower rack being contactable with a manually adjustable stop rod thread edly mounted in a side wall of the said baseplate, the position of the said stop rod being lafiixable by a locking member threadedly mounted thereon and contactable with the external surface of the said side wall, the said driving pinion being biased against disengagement from the said first intermediate spur gear by a compression spring mounted upon the said gear driver shaft between the said pinion and the front wall of the said baseplate, the said gear driver shaft being slidable by manual pressure along its longitudinal axis to a position wherein the said driving said dust and debris being received upona transversely sloping portion of the upper surface of the said baseplate which terminates at the base of a circular aperture located in the rear wall of the said baseplate, said aperture being adapted to communicate with a suitable suction tube, the said cooling fans also cooperating with the said guard to blow dust and debris escaping from the area between pinion is disengaged from the said first intermediate spur gear, the said hand lever being turnable in this disengaged position to any desired angular location, the said compression spring cooperating to re-engage the said driving pinion with the said first intermediate spur gear when the desired angular location has been reached and the said manual pressure has been released, the said baseplate also supporting, in cooperation with a bracket mounted upon the front side of the said baseplate, at its central portion, a horizontal frame disposed transversely to the longitudinal axis of the baseplate and also incorporating upon its upper surface a horizontal guide bar engageable with a removable frame having a grooved lower portion aflixed to an inverted U-shaped upper portion having a suitable handle and threadedly mounting a plurality of adjustable clamps attached to at least one movable strap, the said strap being contactable with a suitable work holder adapted to projectably receive within a number of holes therein a plurality of coiled compression springs, the said upper portion also having a plurality of threaded holes adapted to receive and removably retain a wheel dresser contactable with the said grinding discs, the said grinding discs being simultaneously contactable with the projecting ends of the said springs and with each other when the said frame is removed from the space between the said grinding heads, the said baseplate also supporting above the said grinding discs a thin sheet-like guard suitably stiffened and having a cross-sectional conformation of an inverted U, the said guard having open sides and a pair of laterally adjustable, hinged front members which incorporate at least one lifting knob, the said guard confining dust and debris within the vicinity of the said grinding discs, the

the grinding heads back into the said area.

15. An improved spring grinder comprising in combination a pair of horizontally aligned, direct driven grinding heads each of which has a grinding disc with an unperforated grinding surface, a circular plate afiixed to the said disc and attached to a suitable hub mounted upon the shaft of a motor having a suitable thrust bearing and a partially enclosed cooling fan which cooperates with the said motor to circulate a cooling flow of air thereabout, the said grinding heads each being independently rotatable in a forward as well as a reverse direction and operable by a suitably mounted electrical control switch, the said motor being suitably mounted upon a rectangular plate slidably retained within a pair of parallel ways mounted upon the upper surface of a hollow baseplate supported upon a vibration absorbent cushion and having a front wall and a split vertical member integral with the upper surface of the said baseplate rotatably retaining within the said baseplate a gear driver shaft turnable by a suitable hand lever aflixed upon the front end thereof, the said shaft also extending within the interior of the baseplate and having a driving pinion afiixed thereon and engaged with a first intermediate spur gear aflixed upon a parallel intermediate shaft, said intermediate shaft also having an intermediate pinion aflixed thereon and engaged with a second intermediate spur gear afiixed upon a parallel driven shaft, the said driven shaft also having a driven pinion affixed thereon and concurrently engaged with upper and lower horizontal racks, the said upper rack being mounted upon a block slidably located within a first longitudinal slot in the upper surface of the said baseplate and disconnectably bolted to the lower surface of one of the said rectangular plates, the said lower rack being supported by a roller suitably mounted upon the said first intermediate shaft, the said lower rack also being secured to a horizontal angle member which is in turn mounted upon a second block slidably located within a second slot in the upper surface of the said baseplate and disconnectably bolted to the lower surface of the other of the said rectangular plates, the said lower rack being contactable with a manually adjustable stop rod threadedly mounted in a side wall of the said baseplate, the position of the said stop rod being aflixable by a locking member threadedly mounted thereon and contactable with the external surface of the said side wall, the said roller, driven pinion and upper and lower racks being retained between the split portions of the said vertical member, the said driving pinion being biased against disengagement from the said first intermediate spur gear by a compression spring mounted upon the said gear driver shaft between the said pinion and the front wall of the said baseplate, the said gear driver shaft being slidable by manual pressure along its longitudinal axis to a position wherein the said driving pinion is disengaged from the said first intermediate spur gear, the said hand lever being turnable in this disengaged position to any desired angular location, the said compression spring cooperating to re-engage the said driving pinion with the said first intermediate spur gear when the desired angular location has been reached and the said manual pressure has been released, the said baseplate also supporting, in cooperation with a bracket mounted upon the front side of the said baseplate, at its central portion, a horizontal frame disposed transversely to the longitudinal axis of the baseplate and also incorporating upon its upper surface a horizontal guide bar engageable with a removable frame having a grooved lower portion afiixed to an inverted U- 11 shaped upper portion having a suitable handle and threadedly mounting a plurality of adjustable clamps attached to at least one movable strap, the said strap being contactable with a suitable work holder adapted to projectably receive within a number of holes therein a plurality of coiled compression springs, the said upper portion also having a plurality of threaded holes adapted to receive and removably retain a wheel dresser contactable with the said grinding discs, the said grinding discs being simultaneously contactable with the projecting ends of the said springs and with each other when the said frame is removed from the space between the said grinding heads, the said baseplate also supporting above the said grinding discs a thin sheet-like guard suitably stiffened and having a cross-sectional conformation of an inverted U, the said guard having open sides and a pair of laterally adjustable, hinged front members which incorporate at least one lifting knob, the saidtguard confining dust and debris within the vicinity of the said grinding discs, the said dust and debris being received upon a transversely sloping portion of the upper surface of the said baseplate which terminates at the base of a 16. In a grinding machine of the class described, in combination, a pair of coaxially disposed, direct motor driven grinding heads having their grinding faces arranged in spaced confronting relation, a dust shield disposed around the area between said grinding faces, a dust collector disposed below said grinding area and communicating therewith, and an air circulating fan mounted axially on each of said grinding heads exteriorly thereof and operable during rotation of the grinding heads to provide a flow of cooling air axially inward over the motors toward the area between the grinding faces and cooperating with the said dust shield to confine dust and debris to the said area and the dust collector.

References Cited in the file of this patent UNITED STATES PATENTS 1,416,952 Gardner May 23, 1922 1,589,593 Gardner June 22, 1926 1,992,452 Troendly Feb. 26, 1935 2,142,444 Hall Jan. 3, 1939 2,246,869 T roendly et al June 24, 1941 2,329,995 Koether Sept. 21, 1943 2,375,333 Troendly et a1. May 8, 1945 FOREIGN PATENTS 530,625 Great Britain Dec. 17, 1940 

